Amorphous hydrogenated carbon (a-C:H), also known as diamond-like carbon for its superior hardness, has many useful properties such as chemical inertness, high wear resistance, high resistivity and low dielectric constant (k&lt;3.6). For instance, in a paper "Diamond-Like Carbon Materials As Low-k Dielectrics" published in Proc. Advanced Metalization and Interconnect Systems for ULSI Applications (1996), by Materials Research Society, Pittsburgh, Pa. 1997, such desirable properties were discussed. DLC films can be fabricated by a variety of techniques including physical vapor deposition or sputtering, ion beam sputtering and DC or RF plasma assisted chemical vapor deposition with precursors of a variety of carbon-bearing source materials. U.S. Pat. No. 5,559,369, assigned to some of the common assignees of the present invention, further discloses diamond-like carbon for use in VLSI and ULSI interconnect systems.
The continuous shrinking in dimensions of electronic devices utilized in ULSI circuits in recent years has resulted in increasing the resistance of the back-end-of-the-line (BEOL) metalization as well as increasing of the intralayer and interlayer capacitances. This combined effect increases signal delays in ULSI electronic devices. In order to improve the switching performances of future ULSI circuits, low dielectric constant insulators and particularly those with k significantly lower than that of silicon oxide are needed to reduce the capacitances. Dielectric materials that have low k values are available, for instance, polytetrafluoroethylene (PTFE) with k value of 2.0. However, these dielectric materials are not stable at temperatures above 300.sup..about. 350.degree. C. which renders them useless during integration of these dielectrics in ULSI chips which require thermal stability at temperatures of at least 400.degree. C. DLC materials have been previously considered as a possible low-k dielectric, however, the films have either been found not stable at temperatures above 300.degree. C., or have dielectric constants significantly higher than 3.6.
It is therefore an object of the present invention to provide a method for fabricating a thermally stable carbon-based low dielectric constant film that does not have the drawbacks or shortcomings of the conventional methods.
It is another object of the present invention to provide a method for fabricating a thermally stable carbon-based low dielectric constant film from a cyclic hydrocarbon precursor.
It is a further object of the present invention to provide a method for fabricating a thermally stable carbon-based low dielectric constant film in a parallel plate plasma enhanced chemical vapor deposition chamber.
It is another further object of the present invention to provide a method for fabricating a thermally stable diamond-like carbon film of low dielectric constant for use in electronic structures as an intralevel or interlevel dielectric in a back-end-of-the-line interconnect structure.
It is still another object of the present invention to provide a method for fabricating a thermally stable diamond-like carbon film of low dielectric constant capable of sustaining a process temperature of at least 350.degree. C. for four hours.
It is yet another object of the present invention to provide a thermally stable diamond-like carbon film of low dielectric constant that has low internal stresses and a dielectric constant of not higher than 3.6.
It is still another further object of the present invention to provide an electronic structure incorporating layers of insulating materials as intralevel or interlevel dielectrics in a back-end-of-the-line wiring structure in which at least two of the layers of insulating materials comprise diamond-like carbon film.
It is yet another further object of the present invention to provide an electronic structure which has layers of diamond-like carbon films as intralevel or interlevel dielectrics in a back-end-of-the-line wiring structure which further contains at least one dielectric cap layer as a RIE MASK polish stop or a diffusion barrier.